The results of measuring the charge-discharge characteristics of solid-state thin-film lithium-ion batteries with a nanocomposite anode based on a-Si(Al) solid solution are presented. The charging characteristics of batteries have a feature in the form of a step on the smooth branch of the charge curve. It is shown that the appearance of the step is associated with the compensation of a-Si(Al) and the change from hole to electron conductivity due to lithiation of the electrode during charging. As a result of lithiation, the electron over-barrier current becomes the main component of the charging current. To maintain a galvanostatic charge mode, the potentiostat increases the voltage by the height of the potential barrier, which leads to the appearance of a step on the charging curve. The impedance of a solid-state thin-film lithium-ion battery of the LiCoO2–LiPON–Si@O@Al electrochemical system was measured in the temperature range from –20 to 50°C. A structural model of the accumulator is proposed and the parameters of the structural elements of the model are calculated which provide the best fit for experimental Nyquist diagrams. The obtained values of the electrodes’ resistivity are orders of magnitude higher than the results of direct measurements and data from literary sources. According to the IV-characteristics obtained by cyclic voltammetry the high resistance of the electrodes is due to the metal-semiconductor contact and the varistor effect of the electrode material. The results obtained make significant adjustments to the interpretation of the impedance spectra and structural models of solid-state lithium-ion batteries based on semiconductor materials.

The purpose of this work is to study the characteristics of the junction between the titanium down conductor of a thin-film solid-state lithium-ion battery (a-Si) and a negative Si@O@Al nanocomposite electrode. The results of measuring the band gap of the Si@O@Al nanocomposite and the height of the Schottky barrier of the Ti–Si@O@Al junction are presented. The transmission and reflection spectra of Si@O@Al films and its main phases a-Si, a-SiOx, and a-Si(Alx) are studied. The band gap of Si@O@Al was determined by the Tauc method, which is 1.52 eV for a-Si and 1.15 eV for nc-Si. The IV characteristics of Ti‒Si@O@Al, Ti–a-Si, Ti–a-SiO0.8, and Ti–a-Si0.9(Al0.1) structures have been studied and the height of the Schottky barrier has been determined. The results obtained make it possible to estimate the Fermi energy of the nanocomposite and to interpret the hike in the SSLIB charging voltage as a result of the Al acceptor impurity compensation during lithiation. A change in the majority charge carriers in Si@O@Al leads to a decrease in the hole current and an increase in the density of the over-barrier electron current, as a result of which a step with a height of 1.5 V is formed on the charging curve.

The influence of nonuniformity properties of the LiCoO2 cathode film deposited by magnetron sputtering on the capacity of all-solid-state thin-film lithium-ion batteries (ASSLIB) was studied. It was found that the film nonuniformity corresponds to the magnetron plasma density distribution and the angular distribution of sputtered particles. The capacity distribution of the ASSLIB with LiCoO2 cathode depending on the distance to the substrate center was studied. The maximum capacity corresponded to the dense part of the toroidal region of the magnetron plasma. It was determined that the main causes of batteries capacity decline in the central part and on the edge of the substrate are the impurity phase of lithium cobaltate and the smaller thickness of the cathode layer, respectively.

The results of measuring the charge-discharge characteristics of solid-state thin-film lithium-ion batteries with a nanocomposite anode based on a-Si(Al) solid solution are presented. The charging characteristics of batteries have a feature in the form of a step on the smooth branch of the charge curve. It is shown that the appearance of the step is associated with the compensation of a-Si(Al) and the change from hole to electron conductivity due to lithiation of the electrode during charging. As a result of lithiation, the electron over-barrier current becomes the main component of the charging current. To maintain a galvanostatic charge mode, the potentiostat increases the voltage by the height of the potential barrier, which leads to the appearance of a step on the charging curve. The impedance of a solid-state thin-film lithium-ion battery of the LiCoO2-LiPON-Si@O@Al electrochemical system was measured in the temperature range from -20°С to 50°С. A structural model of the accumulator is proposed and the parameters of the structural elements of the model are calculated which provide the best fit for experimental Nyquist diagrams. The obtained values of the electrodes’ resistivity are orders of magnitude higher than the results of direct measurements and data from literary sources. According to the IV-characteristics obtained by cyclic voltammetry the high resistance of the electrodes is due to the metal-semiconductor contact and the varistor effect of the electrode material. The results obtained make significant adjustments to the interpretation of the impedance spectra and structural models of solid-state lithium-ion batteries based on semiconductor materials

The results on measuring the impedance of a solid-state thin-film lithium-ion battery of the Si@O@Al-LiPON-LiCoO2 electrochemical system in the temperature range from -20oC to +50oC are presented. A structural model is proposed and the parameters of its elements, providing the best fit for the experimental Nyquist diagrams, are calculated. It is shown that the main contribution to the internal resistance is made by the LiPON-LiCoO2 interface. Based on the temperature dependence of the LiPON solid electrolyte conductivity the activation energy of lithium is determined, which is in good agreement with the literature data. Keywords: Nanocomposite, lithium-ion battery, impedance spectroscopy, structural model, ionic conductivity.

The results on measuring the impedance of a solid-state thin-film lithium-ion battery of the LiCoO2-LiPON-Si@O@Al electrochemical system in the temperature range from -20°С to 50°С are presented. A structural model is proposed and the parameters of its elements, providing the best fit for the experimental Nyquist diagrams, are calculated. It is shown that the main contribution to the internal resistance is made by the LiPON-LiCoO2 interface. Based on the temperature dependence of the LiPON solid electrolyte conductivity the activation energy of lithium is determined, which is in good agreement with the literature data.

The results of measuring the resistivity of thin-film structures Ti|Si@O@Al|Ti and Ti|LiCoO2|Ti by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) are presented. It was found that, according to the EIS data, the resistance of Ti|Si@O@Al|Ti is three orders of magnitude higher than the CV data, which is due to the nonohmic nature of the metal-semiconductor junction and the varistor effect. It is shown that the Ti-LiCoO2 contact is ohmic, while the nonlinearity of the CVC is well described by the varistor effect. The results obtained are of importance for the interpretation of the impedance spectra of thin-film solid-state lithium-ion batteries based on semiconductor materials.

The results on measuring the I-V characteristics of the metal-semiconductor transition within the Ti(200nm)|Si@O@Al(179nm)|Ti(203nm) test structure are presented. The basis of the Si@O@Al nanocomposite is a solid solution of Al in amorphous silicon a-Si(Al). The I–V of the test structure has a form characteristic of a reverse-biased ohmic contact between a metal and a p-type semiconductor, which implies that a-Si(Al) is a substitutional solid solution. It is shown that the I-V fits well the framework of the metal-semiconductor transition model and the varistor effect of the nanocomposite. Within the framework of the percolation model, it is shown that the I–V give values of the Si@O@Al resistivity, which are overestimated with respect to the resistance of the a-Si(Al) solid solution.

The results on measuring the I--V characteristics of the metal-semiconductor transition within the Ti (200 nm)|Si@O@Al (180 nm)|Ti (203 nm) test structure are presented. The basis of the Si@O@Al nanocomposite is a solid solution of Al in amorphous silicon a-Si(Al). The I--V of the test structure has a form characteristic of a reverse-biased ohmic contact between a metal and a p-type semiconductor, which implies that a-Si(Al) is a substitutional solid solution. It is shown that the I--V fits well the framework of the metal-semiconductor transition model and the varistor effect of the nanocomposite. Within the framework of the percolation model, it is shown that the I--V give values of the Si@O@Al resistivity, which are overestimated with respect to the resistance of the a-Si(Al) solid solution. Keywords: nanocomposite, amorphous silicon, solid solution, Schottky barrier, nonlinear conductor, dangling bonds.

A method to form tapered structures via the cyclic plasma-chemical etching of silicon using a spherical photoresist mask is described. The method is based on the possibility of controlling the structure profile by adjusting the silicon and photoresist etching selectivity. In this study, to control the selectivity value, each cycle of the well-known two-stage Bosch silicon etching process is supplemented with a third stage, namely, photoresist etching in oxygen-containing plasma. A model of transformation of the photoresist-mask contour during etching is developed using the experimental results. The parameters of the additional stage are calculated for each silicon etching cycle in terms of model concepts. The result is the formation of tapered structures with a sidewall taper angle close to the target value.

Experimental data on the generation and detection of characteristic X-radiation of elements in electron probe microanalysis of dielectric samples in the low vacuum mode without the deposition of conducting coatings are discussed. The main advantage of the considered method of analysis is the stability of the intensity ratio between diagnostic analyte lines in the wide range of currents of the electron probe and gas phase pressure in the chamber in the range 60–130 Pa, sufficient for obtaining undistorted images of the surface of dielectrics. The stability of the intensity ratio ensures obtaining correct data of the quantitative analysis of nonconducting samples without the deposition of conducting coatings. The main features of low-vacuum microanalysis for the range of gas phase pressures used are discussed, which can create additional difficulties in the study. Among such features is a possibility of the manifestation of reflexes of gas-phase elements, significant underestimation of the relative emission intensity from lighter elements in the composition of the studied samples, loss of scanning locality in the analysis of small sites on the sample surface. An example of the correct quantitative elemental analysis of a dielectric surface without the deposition of an electroconductive coating for a number of aluminosilicates is presented.